MADRID (AP) — One side likens the other to North Korea and promises “hell will freeze over” before it surrenders. Its adversary speaks darkly of “abhorrent” deeds and an “environmental crime.”

It sounds like a dangerous blow-up between arch-enemies. But the opponents in this fight are just testy neighbors: Spain and the British domain of Gibraltar.

In question is an artificial reef that Gibraltar created offshore to block what it calls excessive Spanish fishing in its waters, a move that caused Spain to retaliate by beefing up border security, creating excruciating delays for cars going in and out of the tax-free haven. At the heart of the dispute is a longstanding row surrounding Spain’s claims to sovereignty over Gibraltar, an issue that invariably stirs Spanish passions and boils over every decade or so with arguments such as the one over the reef.

Gibraltar’s chief minister, Fabian Picardo — accusing Spain of bullying the tiny enclave like a belligerent North Korea — claims that Spanish Prime Minister Mariano Rajoy is using the fishing issue to fan nationalist sentiment so Spaniards will forget their economic misery and a corruption scandal slamming his party, a charge echoed by Spanish opposition politicians. If that’s Rajoy’s strategy, it appears to be working: The Gibraltar flap has become Spain’s top news story, dominating front pages and television newscasts — bumping the scandal off the agenda.

Amid the noise, experts say one thing appears certain: The Gibraltar tussle won’t ruin relations between Spain and Britain — even as the two countries remain at loggerheads over ownership.

“I think Gibraltar is and will continue to be a point of friction but I doubt that it will strain relations between the two countries to the point of a breakup,” said Antonio Barroso, a London-based analyst with Teneo Intelligence political and business risk firm. “Spain and the U.K. have far too many interests in common to let Gibraltar be the defining issue of their relationship.”

The dispute erupted last month when barge workers dumped 70 boulder-sized concrete blocks into the sea just off of Gibraltar’s lone airport runway — creating an artificial reef in the name of environmental protection. It triggered the most notable British-Spanish crisis over “The Rock” since 2004, when Spain protested festivities celebrating the 300th anniversary of the Anglo-Dutch invasion of Gibraltar.

Spanish Interior Minister Jorge Fernandez Diaz called the artificial reef “abhorrent” and “a very clear environmental crime,” while Picardo said “hell will freeze over” before the blocks are removed.

In addition to the security checks, Rajoy’s conservative administration has threatened to impose a Gibraltar entry tax and regulate Gibraltar’s lucrative ship refueling industry. He has also demanded a stop to smuggling into Spain of cheap cigarettes bought in Gibraltar and warned of possible tax fraud investigations targeting Gibraltar residents who own homes in southern Spain.

The European Commission said this week that it hopes Britain and Spain will be able to resolve their latest dispute over Gibraltar by themselves, but agreed to send a fact-finding team to the territory of 30,000 people next month to investigate, while saying Spain’s idea of a Gibraltar entry fee would be illegal. But experts doubt a resolution will happen anytime soon because London is committed to Gibraltarians’ desires to remain a British territory.

“This is a classic escalation of tensions, you have a macro issue of sovereignty with a mid-level fishing issue problem,” said Barroso. “Tensions will continue because it is very difficult to find a solution.”

Underlying the dispute is the Treaty of Utrecht signed by Britain and Spain on July 13, 1713, which saw Spain buckle following the War of Spanish Succession and gave Gibraltar to Britain “with all manner of right for ever, without any exception or impediment.”

The treaty also mandated never-enforced clauses requiring Britain to prevent “Jews or Moors” from living in Gibraltar and barring “Moorish ships of war” from entering the harbor so Spain’s coast would not “be infested by the excursions of the Moors.”

But it didn’t mention anything about control over its waters — and Gibraltar’s insistence that its territorial waters extend 3 nautical miles (5.6 kilometers) has never been accepted by Spain. That has led to low level cat-and-mouse skirmishes since 2009, with Gibraltarian patrol boats chasing Spanish vessels casting nets in places Gibraltar says are its own. The latest twist was the creation of the reef.

“What is interesting is that the current dispute is about fishing but it is being used to discuss territorial waters and what those limits are for Gibraltar,” said Chris Grocott, a historian at Britain’s University of Leicester and co-author of “Gibraltar: A Modern History.”

“It is being used as an opening to the larger issues.”

While Rajoy has managed to appear tough to the Spanish public over Gibraltar, he now runs the risk of triggering a new round of bickering with Morocco over the North African kingdom’s longstanding claims that Spain should give up its North African enclaves of Ceuta and Melilla, which are surrounded by Morocco and the Mediterranean Sea — much in the way Gibraltar is tucked into Spain.

To many non-Spaniards, “it seems ridiculous that Spain has territory there,” said Pablo Perez Lopez, a history professor at Spain’s University of Navarra. “But the position of Spain is that it was in North Africa hundreds of years before the British arrived in Gibraltar.”